National says it would complete the construction of the Waikato expressway within 10 years.
The expressway is a 95km, four lane highway between Auckland and Hamilton.
Some parts have already been built and funding is already allocated for other sections.
National Party leader John Key says his party would commit the necessary $790 million towards its completion.
The funding would come from additional infrastructure spending already flagged by the party.
Mr Key says the expressway would be of "national significance", which means consents could be fast-tracked.
He says there would be no tolling on the new expressway.
